JOHANNESBURG (Reuters) - The number of rhinos killed by poachers has hit a new annual record in South Africa, raising worries of a downward population spiral in a country that is home to almost all of Africa's rhinos.

As of the end of September, 704 rhinos had been killed by poachers in South Africa, exceeding the annual record of 668 set in 2012, according to data provided by the Environmental Affairs ministry on Tuesday.